The Department of Cancer Biology was created 4 years ago, almost to the day, with the goal of gathering cell and molecular biologists with a focus on interactions between cancer cells and their microenvironment, particularly with regard to tumor invasion. Dr. Lynn Matrisian, the Chairperson, has substantially succeeded in realizing this goal by recruiting senior and junior faculty with diverse but complementary expertise in host-tumor interactions. The result is a tightly-knit group with complementary but distinct interests and expertise in the field of cancer invasion. The Richmond laboratory is a world-leader in original approaches to studying tumor cell chemotaxis regulated by chemokine receptors. The Reynolds laboratory is perhaps the leading lab in the country, at this stage, in studies on cadherin-mediated regulation of epithelial cell adhesion. The Weaver laboratory focuses on cytoskeletal reorganization, particularly as it pertains to the formation of subcellular structures for cancer invasion and metastasis (e.g. lamellipodia, invadopodia and podosomes). The Quaranta laboratory is a leader on extracellular matrix, basement membrane invasion and laminin-binding integfins. The Matrisian laboratory has made fundamental contributions to our understanding ofproteinases in cancer invasion, and is currently focused on mouse models for human cancer. Laboratories affiliated with Cancer Biology (via secondary appointments) that are eoinvestigators in this proposal include the Pozzi lab (studying angiogenesis and ECM in mouse models of cancer), the Chen lab (Eph receptors in mammary carcinogenesis), the Arteaga laboratory (TGF-[_, proliferation, apoptosis, invasion in mammary carcinogenesis, along with mouse models of human cancer).